Magnetic core selection arrangement



E. E. NEWHALL MAGNETIC CORE SELECTION ARRANGEMENT Nov. 18, 1969 4 Sheets-Sheet 1 Filed Sept. 19, 1966 lNVENTOR By E.E.NEWHALL A T TOR/V5 5 NOV. E, NE H MAGNETIC CORE SELECTION ARRANGEMENT 4 Sheets-Sheet 2 Filed Sept. 19, 1966 MW b l tiara? Q n Nh m Nov. 18, 1969 E. NEWHA'LL MAGNETIC CORE SELECTION ARRANGEMENT 4- Sheecs-Sheet 5 Filed Sept. 19, 1966 3w Sm mm B? M Aw w mmm 3 an 85% M858 L m uw a o w v Ewwm u PE KS r G L 5% mwm E. E. NEWHALL MAGNETIC CORE SELECTION ARRANGEMENT Nov. 18, 1969 4 Sheets-$heet 4 Filed Sept. 19, 1966 United States Patent 01 hce 3,479,658 Patented Nov. 18, 1969 3,479,658 MAGNETIC CORE SELECTION ARRANGEMENT Edmunde E. Newhall, Brookside, N..l., assignor to Bell Telephone Laboratories, Incorporated, Murray Hill and Berkeley Heights, N.J., a corporation of New York Continuation-impart of application Ser. No. 241,375, Nov. 30, 1962. This application Sept. 19, 1966, Ser.

Int. Cl. Gllb 5/00 U.S. Cl. 340174 33 Claims ABSTRACT OF THE DISCLOSURE An arrangement for selectively energizing one of a plurality of switching devices includes an array of multiapertured magnetic cores. Each core has a set of selection windings and a switching winding coupled thereto, each such winding extending through a different aperture. Selected sections of the magnetic material extending between the periphery of an aperture and the outer extremity of the core are removed contiguous to certain apertures of each core, no two of the cores having identical patterns of removed sections. A core is selected by coincidentally energizing the switching winding coupled to the core and specified ones of the selection windings. Only one of the cores includes a removed section associated with each aperture through which an energized selection winding extends. This selected core is therefore not inhibited from switching. Accordingly, the selected core is switched from one to another magnetic flux condition while the remaining cores are blocked from switching and therefore do not have their initial conditions altered.

This application is a continuation-in-part of my copending United States application, Ser. No. 241,375, filed Nov. 30, 1962, now abandoned.

This invention relates to magnetic core selection and, more specifically, to arrangements for changing the hysteresis remanent condition of a selected one of a plurality of square loop, ferromagnetic cores.

Various circuits which employ a plurality of magnetic cores, either toroidal or multiapertured in nature, require a selection of one of the plurality of cores. Such circuits include, for example, memory and storage arrangements, binary counters, shift registers, and converging switches.

Prior art circuit embodiments have employed several techniques to accomplish a core selection. Possibly the most extensively employed selection arrangement is to interconnect the plurality of cores in a dual axis matrix array with a pair of windings, one for each of the matrix axes, coupled to each core. A single energized winding coupled to a core produces a magnetizing force which switches only a negligible shuttle flux and partially selects a core, while two coincident energized core windings will switch the remanent condition of the selected core. The fabrication of such an arrangement, however, requires rather complex circuitry including relatively cumbersome and extensive wiring interconnections. In addition, the dual axis, matrix type of selection is limited to core cir cuits which are driven between maximum remanent hysteresis polarities.

It is therefore an object of the present invention to provide improved arrangements for selecting one of a plurality of ferromagnetic cores.

More specifically, it is an object of the present invention to provide improved core selection circuits wherein the magnetic condition of only a selected one of a plurality of ferromagnetic cores is altered in response to a given combination of digital input signals.

Another object of the present invention is the provision of magnetic core selection arrangements which may be simply constructed and are relatively inexpensive.

These and other objects of the present invention are realized in specific illustrative magnetic core arrangements including a plurality of square loop ferromagnetic cores, each including a flux driving leg. A plurality of apertures are placed in the driving leg of each core, and a plurality of common selection windings are threaded therethrough, each winding being linked to a corresponding aperture on each core. Selected sections of the ferromagnetic material extending between the periphery of an aperture and the outer extremity of the core are removed contiguous to selected apertures on each core, no two of the cores having identical patterns of removed sections.

In one of the illustrative magnetic core arrangements, the driving leg of each core is initially in a neutral magnetic condition and a core is selected by energizing certain ones of the plurality of selection windings. If an energized winding passes through a core aperture which is not adjacent to a removed section, the resulting flux flowing around the aperture holds the core material surrounding the aperture in a saturated condition, and effectively blocks any flux from being switched in the core. The selected core, however, remains unblocked as it includes a removed section associated with every aperture coupled to an energized selection winding. When a switching magnetomotive force is coincidentally supplied to each of the cores, only the driving leg of the selected, unblocked core will switch its magnetic condition from its initial neutral magnetic state to a condition of remanent saturation.

In other illustrative selection arrangements made in accordance with the principles of the present invention, the driving leg of each core is initially in a saturated magnetic condition, and only the driving leg of the selected unblocked core switches to a neutral magnetic state. In addition, alternative selection schemes utilize core sections removed from different portions of the ferromagnetic material surrounding the selection apertures, rather than the presence or absence of removed sections.

It is thus a feature of the present invention that a core selecting arrangement include a plurality of ferromagnetic cores, a plurality of apertures located in one leg of each core, and a plurality of windings each of which is coupled to a corresponding aperture included in each core, wherein certain portions of the ferromagnetic material contiguous to certain apertures are removed.

It is another feature of the present invention that a magnetic core selecting arrangement include a plurality of square loop ferromagnetic cores and a plurality f selection windings coupled to each core, wherein certain ones of the selection windings are linked to an individual core by a relatively high reluctance magnetic path, and the remainder of the windings are coupled thereto by a relatively low reluctance magnetic path, no two of the cores having an identical pattern of relatively high and low reluctance couplings.

A complete understanding of the present invention and of the above and other features, variations and advantages thereof, may be gained from a consideration of the following detailed description of several illustrative embodiments thereof presented hereinbelow in connection with the accompanying drawing, in which:

FIG. 1 is a specific illustrative magnetic core selection arrangement which embodies the principles of the present invention;

FIG. 2 is a diagram depicting the various magnetic conditions of the plurality of driving legs illustrated in FIG. 1;

FIG. 3 is an alternative specific illustrative magnetic core selection arrangement which embodies the principles of the present invention; and

FIG. 4 is still another alternative specific illustrative magnetic core selection arrangement which embodies the principles of the present invention.

Referring now to FIG. 1, there is shown a specific illustrative magnetic core selection arrangement employing a plurality of ferromagnetic multiapertured cores 50 through 53. Each core includes a driving leg 20, a shunt leg 21 connected in parallel with the driving leg, and two cross legs 22 each of which includes a plurality of apertures 35 located on the long axis thereof. Coupled to each of these apertures 35 is an input winding 37 and an output winding 39 which links the ferromagnetic material on either side of the aperture 35 in an opposite polarity. To avoid congesting FIG. 1 of the drawing, the windings 37 and 39 are shown coupled to only one aperture 35 included in the core 50. It is to be understood, however, that each aperture 35 in each of the cores 50 through '53 has similar windings 37 and 39 coupled thereto.

It is noted that binary input information to the core arrangement shown in FIG. 1 is manifested by the presence or absence of a current supplied to each input winding 37.

The operation of the cores 50 through 53 (without the removed sections) is set forth in detail in my joint application with J. N. Brown, ]r., Ser. No. 241,442, filed Nov. 30, 1962, now Patent 3,457,553, issued July 22, 1969. Briefly, when one of the cores 50 through 53 undergoes a change in the amount of flux stored in its driving leg 20, a similar change in remanent flux transpires in the ferromagnetic material in the cross legs 22 which surrounds each of the core apertures 35. In response thereto, a zero net output voltage is induced in an output winding 39 when the corresponding input winding 37 is de-energized. Conversely, an output voltage is generated in an output winding 39 associated with an energized input winding 37. The interconnection of the various input windings 37 and output windings 39 linking the apertures 35 included in the cores 50 through 53 is described in the aforementioned Brown-Newhall application in a converging switch embodiment, and in a counter arrangement and an electronically variable shift register in my applications, Ser. Nos. 241,261 and 241,- 339, respectively, both filed Nov. 30, 1962, now Patent 3,293,621, issued Dec. 20, 1966, and Patent 3,376,562, issued Apr. 2, 1968, respectively. For purposes of the instant invention it is necessary to note only that each of the above-mentioned applications, as well as many other magnetic core arrangements, requires a remanent hysteresis flux change in a driving leg included in a selected one of a plurality of ferromagnetic square loop cores. FIG. 1 illustrates a core arrangement to accomplish this function.

The driving leg included in each of the cores 50 through 53 has four selection apertures through 33 centrally located thereon. Each of the selection apertures shown in FIG. 1 is also designated with a subscript which indicates the particular core containing the aperture.

The core arrangement shown in FIG. 1 includes four selection windings 60 through 63 which are respectively coupled to, and pass through the selection apertures 30 through 33 included in each of the cores through 53. One terminal of each of the windings is grounded, and the other terminals are respectively connected to the x and x output terminals of an X current source 90, and the y and y terminals of a Y current source 91. Each of the sources 90 and 91 supplies a relatively high monopolar current to one of its two output terminals, and a relatively low current to the other of its terminals.

In addition, each of a plurality of switching windings 71 is coupled to a different core driving leg 20 to supply flux in a clockwise switching polarity around the cores. The individual windings 71 are serially interconnected and further joined to a switching current source 73 which supplies monopolar switching current pulses. Also, each of a plurality of reset windings 81 is coupled to one of the cross legs 22 of a different core to supply flux in a counter-clockwise reset polarity around the cores. The individual windings 81 are serially interconnected and further joined to a reset current source 83, which is also connected to each of the selection windings 60 through 63, Following the interrogation of a core, the source 83 supplies a monopolar current pulse to the windings 81 and a current pulse to the windings 60 through 63 of a like polarity as that supplied by the X and Y current sources and 91, which reset the selected core to its initial condition.

One basic aspect of the FIG. 1 selection arrangement is. embodied in the particular configuration of the ferromagnetic material surrounding the apertures 30 through 33 included in each of the cores 50 through 53. Contiguous to selected apertures, a section of the ferromagnetic material between the periphery of the core aperture and the outer circumference of the core structure is removed. Hence, an energized selection winding passing through a core aperture adjacent to a removed section produces a relatively low, negligible flux in that core because of the high reluctance of the open magnetic coupling path. Similarly, an energized winding passing through an aperture not contiguous to a removed section gives rise to a relatively high flux because of the associated closed, relatively low reluctance magnetic coupling path. The sections are removed next to the selected apertures such that each core has a different and unique pattern of removed sections. Table I included hereinbelow indicates the relationship among (a) the currents supplied by the sources 90 and 91 to the x and y terminals, respectively, (b) the selected core, and (c) the location of the removed sections. The numerals 1 and 0, respectively, represent a relatively high and a relatively low current, and the currents supplied to the x and y terminals are, of course, the respective complements of the corresponding x and y quantities.

TABLE I Apertures adjacent to removed sections 31 and 33 31 and 32 30 and 33 30 and 32 The above table is formed simply by numbering the cores in straight binary order, and removing a section whenever a 1 occurs, either for one of the variables x and y, or for their primes, x and y. Hence, it should be observed that although four cores were chosen for convenience, any number might well have been employed. In general, corresponding to a plurality of 2 cores, n selection variables are required, thereby necessitating 2n apertures and selection windings passing therethrough for each core, to represent each selection variable and also its prime.

Before describing a typical sequence of circuit operation, the convention employed in FIG. 2 to illustrate the magnetic condition of the ferromagnetic driving legs 20 will be discussed. Each vector shown represents one unit of flux, all the vectors being of an equal magnitude thereby symbolizing equal fiux values. Also, each of the magnetic driving legs 20 depicted in FIG. 2 has a remanent saturation flux capacity of two units. Hence, when the two vectors are oriented in the same direction the leg is saturated in that direction, and when the arrows are diametrically opposed, the corresponding material is magnetically neutral.

In addition, the shunt leg 21 and the cross legs 22 included in each of the cores 50 through 53 shown in FIG. 1 also each have remanent saturation flux capacities of two units.

To illustrate a typical cycle of operation for the FIG. 1 arrangement, assume that the reset source 83 supplies a current pulse to each of the selection windings 60 through 63 and to the reset windings 81.

The current pulses supplied to the selection windings 60 through 63 by the source 83 generate fluxes which saturate the ferromagnetic material surrounding each core aperture not associated with a removed section to a clockwise remanent condition, while those apertures contiguous to removed sections remain magnetically neutral. This set of initial conditions for the magnetic condition of the driving leg 20 included in each of the cores 50 through 53 following the reset energization is shown by the solid arrows in FIG. 2.

Coincident therewith, the current pulse supplied to the reset windings 81 by the source 83 generates a remanent saturating flux of two flux units in the counter-clockwise direction through the cross legs 22 included in each of the cores 50 through 53. Since flux must be conserved in each junction between any of the magnetic members, the magnetomotive forces produced by the energized reset windings 81 must also generate a remanent saturating flux of two units flowing from right to left in the shunt leg 21 included in each of the cores 50 through 53. As will be explained hereinafter, no portion of the two flux units flowing in the cross legs 22 of each of the cores 50 through 53 can flow through the driving leg 20 thereof, since the driving leg 20 included in each of the cores 50 through 53 is being held in a neutral magnetic condition, with no net flux flowing therethrough, by the simultaneously energized switching windings 60 through 63 coupled thereto. Therefore, the initial magnetic condition of each of the cores 50 through 53 is thereby established, with a remanent saturating flux of two units flowing in a closed magnetic path in the counterclockwise direction through the cross legs 22 and shunt leg 21, the driving leg 20 being in a neutral magnetic condition.

Assume now that it is desired to select the core 51 and drive the leg 20 thereof to a clockwise remanent saturation condition and the legs 22 thereof to a neutral magnetic condition, while the cores 50, 52 and 53 remain in their initial state. To switch the desired core 51, the sources 90 and 91 supply relatively high currents to the x and y terminals, and thereby also to the selection windings 61 and 62, respectively, as indicated in Table I. The actual selective switching is accomplished, as described hereinafter, by the source 73 supplying a switching current to the winding 71 coupled to the driving leg 20 of each core.

Examining the core 50, note that the aperture 32 is coupled to the energized selection winding 62. The magnetomotive force produced by the energized switching winding 71 coupled to the core 50 cannot switch any flux in the ferromagnetic material above the aperture 32 because this material is already saturated in the direction of the applied force. In addition, the winding 71 cannot reverse the flux in the material below the aperture 32 which is held in a saturated condition by the right-to-left magnetomotive force supplied by the continuously energized selection winding 62. Hence, as no flux reversal is possible through any cross-section of the ferromagnetic material surrounding the aperture 32 the leg 20 included in the core 50 is blocked, and it remains in its initial state. In a similar manner, the energized switching winding 71 coupled to the core 52 is prevented from switching any flux therein as the material above both the apertures 31 and 32 is saturated while the material below these apertures is held in reverse saturation by the energized windings 61 and 62, respectively. Further, the energized selection winding 61 coupled to the aperture 31 prevents any flux from switching in the multia'pertured core 53.

Examining the core 51 which is to be selected, however, note that apertures 31 and 32 coupled to the energized 6 windings 61 and 62, respectively, are both contiguous to remove core sections. While the energized winding 71 coupled to the core 51 cannot reverse flux in the material above the apertures 30 and 33 which is in a saturated condition, there is in this instance no externally applied magnetomotive force to prevent the flux below these apertures from switching. Hence, the energized winding 71 switches one unit of flux from a counter-clockwise to a clockwise direction, thereby saturating the leg 20' included in the core 51. It is noted that only one unit of flux is switched as this is the maximum reverse flux available in the ferromagnetic material above the apertures 31 and 32 This new orientation is shown by the dashed arrows for the core 51 in FIG. 2 wherein each cross-section of the driving leg 20 included in the core 51 has a net total of two flux units flowing in a left-to-right direction therethrough.

It is apparent that the energized switching winding "71 must also supply a switching magnetizing force to reverse one flux unit in the cross legs 22 included in the core 51 as no net flux can exist in these members under the above-described magnetic state of the driving leg 20 and the shunt leg 21 included in the core 51. If any flux were contained in the legs 22 it would have to be returned through either the driving leg 20 or the shunt leg 21, as it is an elementary physical principle of magnetics that lines of flux must be continuous. However, the driving leg 20 and the shunt leg 21 included in the core 51 are both in a saturated condition and, moreover, these legs already have two continuous units of flux flowing therethrough in a clockwise direction in a closed, complete magnetic path. Hence, the cross legs 22 of the core 51 are driven by the switching energization from a saturation condition to a neutral magnetic condition.

As described hereinbefore, the change in the flux state of the cross legs 22 included in the core 51 to a neutral magnetic condition induces a zero net output voltage in the output windings 39 when the corresponding input windings 37 coupled to the core 51 are de-energized. Similarly, output voltages are generated in the output windings 39 associated with energized input windings 37.

Reset is accomplished by current pulses supplied to the windings 81 and 60 through 63 by the reset current source 83. The magnetizing forces generated by these windings do not affect the cores 50, 52 or 53 as the apertures of these cores which are not associated with removed sections are already in a clockwise saturated condition around the selection windings 60 through 63, and the driving legs 20 of these cores are in a neutral condition, with their shunt legs 21 and cross legs 22 being saturated in a counter-clockwise direction.'However, the energized windings 60 and 63 coupled to the apertures 30 and 33 respectively, create magnetomotive forces which reverse the left-to-right flux vector in the ferro magnetic material below each of the apertures 30 and 33 and the material surrounding these apertures is reset to its initial clockwise saturation magnetic condition. This, however, creates a not total of zero lines of flux flowing across any cross-section of the ferromagnetic material on each side of both the apertures 30 and 33 Hence, since lines of flux must be continuous, as mentioned above, the remaining material in the driving leg 20 of the core 51 must thereby also be in a net zero magnetization state. coincidentally, the energized winding 81 coupled to one of the cross legs 22 included in the core 51 creates a magnetomotive force which reverses a clockwise flux vector therein, thereby saturating the legs 22 of the core 51 in a counter-clockwise direction, so that two units of remanent saturating flux flow therethrough in a closed magnetic path which includes the shunt leg 21. Thus, the core 51 is returned to its initial condition, illustrated by the solid vectors in FIG. 2, by the reset source 83, and the entire core arrangement is ready to initiate a new cycle of operation.

It is noted at this point, that either one of the energized windings 60 or 63 would have reset the driving leg of the core 51 by interrupting a continuous, left-to-right line of flux below the corresponding aperture 30 or 33 Hence, reset of the driving leg of the selected core could also be accomplished by placing an auxiliary, reset aperture with no adjacent removed section in the driving leg 20 of each core to accomplish this same flux-interrupting function, and coupling thereto a reset winding which is connected to the reset source 83. The reset windings 81 would, however, still be required to reset the cross legs 22 of the selected core.

It should also be noted that a set of initial conditions consistent with the operation of the FIG. I arrangement can be established, and reset can be accomplished without employing the windings 60 through 63, so that the connection between the reset current source 83 and the windings 60 through 63 can thereby be eliminated. To initially set the cores 50 through 53, the switching current source 73 and the reset current source 83 coincidentally supply current. pulses to the switching windings 71 and the reset windings 81, respectively, and the reset source 83 subsequently supplies a second current pulse to the windings 81. The current pulse supplied to the switching windings 71 by the source 73 generates a flux flowing in a clockwise direction through the driving leg 20 included in each of the cores 50 through 53. The first current pulse supplied to the reset windings 81 by the source 83 generates a flux flowing in a counterclockwise direction in the cross legs 22 included in each of the cores 50 through 53. These fluxes flow in the same direction, namely from right to left, through each of the shunt legs 21 included in each of the cores, and moreover, are in combination of sutficient magnitude to produce a remanent saturating flux of two units flowing therein. When the source 83 subsequently supplies a second current pulse to the windings 81, a remanent saturating flux of two units is produced in a counter-clockwise direction through the cross legs 22 included in each of the cores 50 through 53. Each core then has two units of flux flowing from right to left through its shunt leg 21, and returning in a counterclockwise direction through its cross legs 22 in a closed magnetic path. Therefore, since flux must be conserved in each junction between the magnetic members, the driving leg 20 of each core is in a neutral magnetic condition, with no net flux flowing therethrough.

The selected core can be reset to its initial flux condition simply by supplying a current pulse from the reset source 83 to the reset windings 81. The magnetizing forces generated by these windings do not affect the other nonselected cores, as the cross legs 22 thereof are already saturated in the counter-clockwise direction. However, the magnetizing force produced in the winding 81 coupled to a cross leg 22 of the selected core reverses a clockwise flux vector therein, thereby saturating the cross legs 22 thereof in the counter-clockwise direction. Since the shunt leg 21 of the selected core remained in a saturated rightto-left remanent condition through out the selection process, two units of remanent saturating flux flow at this time in a closed magnetic path through the shunt leg 21 and the cross legs 22 of the selected core. The driving leg 20 included in the selected core is therefore driven by the energized reset winding 81 coupled to the selected core to its initial, neutral magnetic condition, in order to conserve the lines of flux throughout the core.

Still another method of establishing the initial conditions for and of resetting the cores 50 through 53 shown in the FIG. 1 arrangement can be employed, In this method each reset Winding 81 is coupled to both a cross leg 22 and the shunt leg 21 included in the core associated therewith, to supply flux in a counter-clockwise direction through these core legs. To initially set the cores 50 through 53, the reset current source 83 supplies a current pulse to the reset windings 81, thereby producing a remanent saturating flux of two units flowing through the cross legs 22 and the shunt leg 21 of each of the cores in a counter-clockwise direction. As explained hereinabove, the driving leg 20 of each of the cores must therefore be driven to a neutral magnetic condition. Similarly, the selected core is reset to its initial magnetic condition by once again energizing the reset winding 81 coupled thereto.

In addition, the flux capacity of the driving leg 20 of each core may advantageously differ from the flux capacity of the legs 21 and 22 thereof. Illustratively, if the flux capacity of the legs 21 and 22 were m units and the flux capacity of the driving leg 20 were k units, then when the driving leg 20 of the selected core is driven to a saturation flux condition, the cross legs 22 of that core would have mk flux units flowing therethrough. As in the mode of operation described above, a zero net output voltage would be induced in an output winding 39 when the corresponding input winding 37 was de-energized, and an output voltage would be generated in an output winding 39 associated with an energized input winding 37. The advantages of operating a core in this manner, when k is relatively small compared to m, are set forth in detail in my aforementioned joint application with J. N. Brown, Jr.

Furthermore, in some modes of operation of the FIG. 1 arrangement the shunt leg 21 included in each of the cores can be eliminated. Then the cross legs 22 of each core would, of course, always be in the same magnetic condition as the material in the driving leg 20 thereof between the apertures 30 through 33. Thus, the driving leg 20 and cross legs 22 of each of the cores 50 through 53 would initially be magnetically neutral, while the selected core would have produced therearound a clockwise remanent saturating flux. Such a configuration could, for example, advantageously be utilized as a selective information blocking arrangement, Before selection of a particular core there would be direct coupling between each input winding 37 and each. output winding 39 coupled to associated apertures 35 in the cross legs 22 of the cores. Since each cross leg would initially be magnetically neutral, every energization change in an input winding 37 would produce a flux perturbation around the associated aperture 35, and hence a net output signal in the output winding 39 coupled thereto. The selected core, however, would block the information contained in the windings 37 coupled thereto so long as it was not reset to its initial condition. Since the cross legs 22 of the selected core would be in a state of remanent saturation, the ferromagnetic material on both sides of each aperture 35 included therein would also have a saturating magnitude of flux flowing therethrough. Currents flowing in the input windings 37 coupled thereto would consequently be unable to create any flux change in that material, and would further be of an insuflicient magnitude to switch the flux state of the entire core. Thus, no voltages would be induced in the associated output windings 39, thereby selectively blocking the input information until the core was reset to its initial neutral magnetic conition.

The above-described arrangement wherein the shunt legs 21 of the cores are eliminated could also be em ployed as a selective readout for an information store. Binary information could be manifested by net flux perturbations around the apertures 35 included in the core cross legs 22 in one or the other of the two possible directions. After the information is read into the core apertures by the energized input windings 37, no outputs would be induced in the windings 39, if there were no change in the stored information and if the cores were not selected. However, in a manner similar to that explained in my aforementioned joint application with J. R. Perucca, Ser. No. 241,339, filed Nov. 30, 1962 now Patent 3,376,562 issued Apr. 2, 1968, when the cross legs 22 of the selected core are driven from a neutral magnetic condition to a state of remanent hysteresis saturation, un-

equal flux changes are produced in the ferromagnetic ma terial on either side of each cross leg aperture 35 thereof, and hence, net output voltages indicative of the stored information are selectively induced in those output windings 39 associated therewith.

Another specific illustrative magnetic core selection arrangement wherein the shunt legs of the cores are omitted, is shown in FIG. 3. Furthermore, the driving leg 320 of each of the cores includes a switching aperture 334, and a single switching winding 372 is coupled to each of the apertures 334. The switching winding 372 is further coupled to the switching current source 373.

The FIG. 3 selection arrangement operates in a manner similar to that of the arrangement in FIG. 1. (Corresponding parts in FIGS. 1 and 3, and also in FIGS. 1 and 4, are identified by reference numerals which are identical except that each such numerals in FIGS. 3 and 4 is prefixed with the digits 3 and 4, respectively.) Each of the apertures 330 through 333 in FIG. 3 which includes a removed core section on the top of the driving leg 320 is coupled to the associated one of the selection windings 360 through 363 by means of the remaining ferromagnetic material surrounding the aperture. Each of the apertures which includes a removed core section on the bottom of the driving leg 320 is not so coupled by the associated selection winding. In addition, it is noted that the pattern of removed core sections from the selection apertures in FIG. 3 can be directly derived from the pattern in FIG. 1 simply by removing a core section on the top side of each aperture in FIG. 1 which is not already contiguous to a removed section. Thus, Table I above is also applicable to the FIG. 3 selection arrangement, where the listing therein of the apertures adjacent to removed core sections specifies the selection apertures with removed core sections on the bottom of the corresponding driving leg 320 in FIG. 3.

To illustrate a typical cycle of operation for the FIG. 3 arrangement, assume that the reset source 383 supplies a current pulse to each of the selection windings 360 through 363, thereby generating a remanent saturating flux in the counter-clockwise direction around each of the cores 350 through 353. Then to select one of the cores, the proper ones of the selection windings are energized, according to Table I, and the switching current source 373 coincidentally supplies a current pulse to the winding 372. If a core has the remaining material surrounding any of its selection apertures coupled by an energized selection winding, the core is blocked and remains in its initial saturated state. The selected core, however, contains no energized selection windings coupled to the remaining material around any of its selection apertures, and remains unblocked. Thus, the energized switching winding coupled to the selected unblocked core produces a saturating flux around the selection aperture 334 therein and drives the leg 320 thereof to a neutral magnetic condition.

It is evident that the flux condition of the cross legs 322 included in any one of the cores 350 through 353 in the FIG. 3 arrangement will always be the same as the magnetic flux condition in the material in the driving leg 320 thereof between the apertures 330 through 333, as there is no shunt leg included in any of the cores. Therefore, the cross legs 322 of the selected core are driven to 'a neutral magnetic state while the cross legs 322 included in each of the other, blocked cores remain in a saturated magnetic condition.

As described hereinbefore for the FIG. 1 selection arrangement, the change in the flux state of the cross legs 322 included in the selected core to a neutral magnetic condition induces a zero net output voltage in the output windings 339 when the corresponding input windings 337 coupled to the selected core are de-energized. Similarly, output voltages are generated in the output windings 339 associated with energized input windings 337.

In FIG. 3 reset is accomplished simply by a current pulse supplied to the windings 360 through 363 by the reset current source 383. The magnetizing forces generated by these windings do not affect the nonselected cores since these cores are already in a counter-clockwise saturated flux condition. However, the energized selection windings coupled to the selected core create a magnetomotive force which again saturates the cross legs 322 and the driving leg 320 thereof to a counter-clockwise remanent condition.

Further, in an alternate resetting method, the connection between the reset current source 383 and the selection windings 360 through 363 can be eliminated, as described hereinabove with reference to the FIG. I arrangement. A reset winding must then be coupled to one of the cross legs 322 included in each of the cores and further connected to the reset current source 383, to supply to the cores a counter-clockwise saturating, reset magnitude of flux.

The FIG. 3 selection arrangement, like the arrangement shown in FIG. 1, utilizes two selection apertures in each core for each of the selection variables x or y and its respective prime, x or y. However, the apertures in each core corresponding to a selection variable and its prime can advantageously be combined into a single aperture, as shown in FIG. 4, thereby halving the number of required selection apertures. The operation of the FIG. 4 selection arrangement is identical to that described hereinabove with reference to the arrangement shown in FIG. 3.

In the above-described arrangements shown in FIGS. 3 and 4 wherein the driving leg and cross legs of the selected core are each driven from a condition of remanent hysteresis saturation to a neutral magnetic condition, it may still be advantageous to employ different magnitudes of flux in the driving and cross legs, for the reason referred to hereinbefore concerning the FIG. 1 selection arrangement. In this case a shunt leg is connected in parallel with each driving leg to provide a closure path for the lines of flux. Illustratively, if the flux capacities of the cross, driving and shunt legs of each core were m, k and m-k units, respectively, where m is greater than k, and if initially it units flowed from left to right in the driving leg, and m units flowed in a clockwise direction in the cross legs, then m-k flux units must flow from left to right in the added shunt leg. Then when the driving leg of the selected core is driven by the energized selection winding to a neutral magnetic condition, the cross legs will have m-k flux units flowing therethrough. As in the mode of operation described above, a net output voltage will be induced in an output winding if and only if the corresponding input winding is energized.

Further, it should be apparent that the fabrication of the selection arrangements shown in FIGS. 1, 3 and 4 is relatively simple, as the cores thereof may be placed in a stacked array with corresponding apertures contained therein being placed one behind the other. With the cores arranged in this manner, threading the selection windings through the apertures becomes a relatively easy and inexpensive operation.

Summarizing the basic features of one of the illustrative magnetic core selection arrangements made in accordance with the principles of the present invention, 2 square loop ferromagnetic cores each have 211 selection apertures located thereon, and Zn common selection windings are threaded through the core apertures. Sections of the ferromagnetic material extending between the outer circumference of an aperture and the outer extremity of the core are removed adjacent to selected apertures on each core, each core possessing a different and unique pattern of removed sections.

A core is selected by energizing certain ones of the Zn selection windings. If an energized winding passes through a core aperture which is not contiguous to a removed section, the resulting flux flowing around the aperture holds the core material surrounding the core aperture in its initial saturated condition and effectively blocks any flux from being switched in the core. The driving leg of the selected core, however, is not held in saturation by any appreciable external magnetomotive force but remains unblocked, as it includes a removed section associated with every aperture coupled to an energized selection winding. When a switching magnetizing force is concurrently supplied to each of the cores, only the selected, unblocked core will switch its magnetic condition.

In other of the illustrative magnetic core selection arrangements, if an energized winding couples the ferromagnetic material surrounding a core aperture which remains after the removal of a core section, the resulting flux holds the entire core in its initial saturated condition and effectively blocks any flux from being switched in the core. The selected core, however, is not held in saturation by any appreciable external magnetomotive force but remains unblocked as the remaining material around its driving leg apertures is not coupled by any energized windings.

It is to be understood that the above-described arrangements are only illustrative of the application of the present invention. Numerous other arrangements may be devised by those skilled in the art without departing from the spirit and scope of the present invention. For example, the selection arrangements described hereinabove are not limited to a multiapertured type of square loop ferromagnetic core. The selection arrangements can be advantageously employed to select one of a plurality of any variety of magnetic cores, whether they possess square loop or linear hysteresis characteristics, and whether they be multiapertured in nature or simple toroids. Furthermore, the arrangements can easily be adapted by those skilled in the art to simultaneously select more than one of a plurality of any of the types of cores mentioned above. In addition, the specific illustrative patterns of removed core sections shown herein can easily be modified, accompanied by corresponding changes in the selection windings coupled thereto. For example, all of the removed sections in the FIG. 3 and FIG. 4 arrangements can be oriented on the same side of the corresponding driving leg, if appropriate winding alterations are made.

What is claimed is:

1. In combination in a magnetic core selection arrangement, a plurality of ferromagnetic square loop cores, each of said cores including a first driving leg and a second leg which completes a closed magnetic path which also includes said first driving leg, a plurality of selection apertures included in each of said driving legs, and a like plurality of selection windings each passing through and being coupled to a different aperture of each of said cores, a selected section of the ferromagnetic material between the periphery of each one of selected core apertures and their respective core extremities being removed, no two cores having identical patterns of removed sections.

2. A combination as in claim 1 further including a plurality of current sources, each of said sources being connected to a different one of said selection windings for selectively supplying thereto either a relatively high or a relatively low monopolar current.

3. A combination as in claim 2 further including a switching current source, and a plurality of switching windings, each of said switching windings being coupled to said driving leg included in a different one of said cores, said switching windings being serially interconnected and further connected to said source of switching current.

4. A combination as in claim 3 further including a plurality of apertures included in each of said second legs, and like pluralities of input and output windings, each pair of windings including one of said input and one of said output windings being respectively associated with and passing through a different one of said apertures included in said second core leg, each of said output windings being coupled to the ferromagnetic material on each side of its associated aperture in an opposite polarity.

5. A combination as in claim 4 further including a plurality of third, shunt ferromagnetic core legs, each of said shunt legs being connected in parallel with a different one of said first driving legs.

6. A combination as in claim 3 further including a reset current source means and a reset winding means coupled to each of said cores, said reset winding means being connected to said reset current source means.

7. A combination as in claim 6 wherein said reset winding means enables said reset current source means to supply a reset current to each of said plurality of selection windings.

8. A combination as in claim 6 wherein said reset winding means is coupled to said second leg included in each of said cores.

9. A combination as in claim 6 wherein said reset winding means is coupled both to said second leg and to said third leg included in each of said cores.

10. In combination in a magnetic core selection arrangement, a plurality of ferromagnetic square loop cores, each of said cores including a first driving leg and a second leg which completes a closed magnetic path which also includes said first driving leg, a switching aperture included in each of said driving legs, a switching winding coupled to each of said switching apertures, a plurality of selection apertures, included in each of said driving legs, and a plurality of selection windings each being coupled to a selection aperture of each of said cores, a section of the ferromagnetic material between the periphery of each of said selection apertures and their respective core extremities being removed.

11. A combination as in claim 10 further including a plurality of current sources, each of said current sources being connected to a different one of said selection windings for selectively supplying thereto either a relatively high or a relatively low monopolar current.

12. A combination as in claim 11 further including a plurality of apertures included in each of said second legs, and like pluralities of input and output windings, each pair of windings including one of said input and one of said output windings being respectively associated with and passing through a diiferent one of said apertures included in said second core leg, each of said output windings being coupled to the ferromagnetic material on each side of its associated aperture in an opposite polarity.

13. A combination as in claim 12 further including a reset current source and a plurality of reset windings, each of said reset windings being coupled to said second leg included in a different one of said cores, said reset windings being serially interconnected and further connected to said reset current source.

14. A combination as in claim 13 further including a plurality of third, shunt ferromagnetic core legs, each of said shunt legs being connected in parallel with a diiferent one of said first driving legs.

15. A combination as in claim 11 further including means for supplying a reset current to each of said plurality of selection windings.

16. A combination as in claim 11 further including a switching current source connected to said switching winding.

17. In combination in a magnetic core selection arrangement, 2 square loop ferromagnetic cores, where n is any positive integer, 2n apertures included in each of said cores, and Zn selection windings coupled to each core, each of said windings passing through and being coupled to a corresponding aperture included in each of said cores, a section of the core material between the periphery of an aperture and the outer core extremity being removed from I: selected apertures included in each of said cores, no two of said cores having the same combination of removed core sections.

18. A combination as in claim 17 further including 2 switching windings, each of said switching windings being coupled to a different core, means for coincidentally energizing each of said switching windings, and n current sources each for supplying a relatively high current and a relatively low continuous current to a different pair of said 2n selection windings.

19. In combination in a magnetic core selection arrangement, 2 square loop ferromagnetic cores, where n is any positive integer, 2n first apertures included in each of said cores, and Zn selection windings coupled to each core, each of said windings passing through and being coupled to a corresponding first aperture included in each of said cores, a section of the core material between the periphery of an aperture and the outer core extremity being removed from each of said first apertures included in each of said cores.

20. A combination as in claim 19 further including a second aperture included in each of said cores, a switching winding coupled to each of said second apertures, means for energiizng said switching winding, and n current sources each for supplying a relatively high current and a relatively low current to a different pair of said 2n selection windings.

21. In combination in 'a magnetic core selection arrangement, 2 square loop ferromagnetic cores, where n is any positive integer, n first apertures included in each bf said cores, and n pairs of selection windings coupled to each core, each of said pairs of selection windings passing through and being coupled to a corresponding first aperture included in each of said cores, a section of the core material between the periphery of an aperture and the outer core extremity being removed from each of said first apertures included in each of said cores.

22. A combination as in claim 21 further including a second aperture included in each of said cores, a switching winding coupled to each of said second apertures, means for energizing said switching winding, and n current sources each for supplying a relatively high current and a relatively low current to a different one of said n pairs of selection windings.

23. In combination, a plurality of ferromagnetic cores, a plurality of selection windings, means for permanently coupling each of said windings to each of certain ones of said cores by a relatively high reluctance magnetic path and to each of the remainder of said cores by a relatively low reluctance path, and a plurality of apertures located on each of said cores in one-to-one correspondence with said selection windings, each of said selection windings passing through a different aperture included in each of said cores, and wherein said relatively high reluctance coupling paths each include a removed section of the ferromagnetic material between the periphery of the corresponding core aperture and the outer extremity of the ferromagnetic core.

24. A combination as in claim 23 wherein each of said cores has a different pattern of removed sections.

25. In combination, a plurality of ferromagnetic cores, a plurality of selection windings, means for permanently coupling each of said windings to each of certain ones of said cores by a relatively high reluctance magnetic path and to each of the remainder of said cores by a relatively low reluctance path, and a plurality of selection apertures located on each of said cores in a one-to-one correspondence with said selection windings, each of said selection windings passing through a different aperture included in each of said cores, a section of the ferromagnetic material between the periphery of each one of said selection apertures and its respective core extremity being removed, said selection winding associated with each of said relatively low reluctance magnetic paths being coupled to the corresponding one of said selection apertures by the remaining ferromagnetic material between the periphery of said corresponding selection aperture and its respective core extremity.

26. A combination as in claim 25 wherein each of said cores has a different pattern of relatively low reluctance magnetic path couplings.

27. In combination, a plurality of ferromagnetic cores, a plurality of selection windings, means for permanently coupling each of said windings to each of certain ones of said cores by a relatively high reluctance magnetic path and to each of the remainder of said cores by a relatively low reluctance path, and a plurality of selection apertures located on each of said cores in a one-to-two correspondence with said selection windings, each pair of two selection windings passing through a different aperture included in each of said cores, a section of the ferromagnetic material between the periphery of each one of said selection apertures and its respective core extremity being removed, said selection winding associated with each of said relatively low reluctance magnetic paths being coupled to the corresponding one of said selection apertures by the remaining ferromagnetic material between the periphery of said corresponding selection aperture and its respective core extremity.

28. A combination as in claim 27 wherein each of said cores has a different pattern of relatively low reluctance magnetic path couplings.

29. In combination, a ferromagnetic core, a plurality of windings, means for permanently coupling certain ones of said windings to said core by a relatively high reluctance magnetic path and the remainder of said windings to said core by a relatively low reluctance path, and a plurality of apertures located in said core in one-to-one correspondence with said windings, each of said windings passing through a different one of said apertures, and wherein said relatively high reluctance coupling paths each include a removed section of the ferromagnetic material between the periphery of the corresponding core aperture and the outer extremity of said core.

30. In combination, a ferromagnetic core, a plurality of windings, means for permanently coupling certain ones of said windings to said core by a relatively high reluctance magnetic path and the remainder of said windings to said core by a relatively low reluctance path, and a plurality of selection apertures located insaid core in a one-to-Qne correspondence with said windings, each of said windings passing through a different one of said apertures, a section of the ferromagnetic material between the periphery of each one of said selection apertures and the outer extremity of said core being removed, said winding associated with each of said relatively low reluctance magnetic paths being coupled to the corresponding one of said selection apertures by the remaining ferromagnetic material between the periphery of said corresponding selection aperture and the extremity of said core.

31. In combination, a ferromagnetic core, a plurality of windings, means for permanently coupling certain ones of said windings to said core by a relatively high reluctance magnetic path and the remainder of said windings to said core by a relatively low reluctance path, and a plurality of selection apertures located in said core in a one-to-two correspondence with said windings, each pair of two windings passing through a different one of said apertures, a section of the ferromagnetic material between the periphery of each of said selection apertures and the outer extremity of said core being removed, said winding associated with each of said relatively low reluctance magnetic paths being coupled to the corresponding one of said selection apertures by the remaining ferromagnetic material between the periphery of said corresponding selection aperture and the extremity of said core.

32. In combination in a magnetic core selection arrangement, a plurality of square loop ferromagnetic cores, means for applying a switching magnetizing force coincidentally to each of said cores, and means coupled to each core for inhibiting switching in all but a selected one of said cores, said inhibiting means including a plurality of 15 selection windings coupled to each core, and means for enabling said selection windings to couple a relatively high or a relatively low inhibiting magnetizing force to each of said cores, no two of said cores having the same pattern of relatively high and relatively low magnetizing force couplings.

33. In combination in a magnetic core selection arrangement, 2 square loop ferromagnetic cores, where n is any positive integer, 2n apertures included in each of said cores, 2n selection windings coupled to each core, each of said windings coupled to one aperture included in each of said cores, means for coincidentally supplying a switching magnetomotive force to all of said cores, n selection current sources, each of said sources supplying a relatively high and a relatively low continuous current to a different pair of said selection windings, and a reset References Cited UNITED STATES PATENTS 10/ 1963 David 340-174 2/ 1966 Hsueh et al 340174 TERRELL W. FEARS, Primary Examiner G. M. HOFFMAN, Assistant Examiner 

